1. The Field of the Invention
This invention relates to a system for managing deliver of parenteral fluids and, more particularly, to a system for managing deliver of contrast media.
2. The Relevant Technology
Contrast media is widely used in a variety of medical procedures typically involving catheterization. In such procedures, the catheter serves to deliver the contrast media to canals, vessels, passage-ways or other body cavities. Contrast media may also be used in association with dilatation catheters in which case the contrast media is contained within the catheter rather than being delivered into the patient. Contrast media may also be injected in other fashions. Regardless of the means of deliver, the contrast media serves the same function in each procedure. Specifically, the contrast media serves to provide a substance which can be viewed by medical personnel rising monitoring apparatus used in conjunction with the particular procedure. For example, contrast media can allow medical personnel to view a variety of different conditions, or lack thereof, on x-ray equipment.
A concern common to all procedures utilizing contrast media is the high cost of the contrast media itself. It is a relatively rare occasion for a procedure to use an exact number of bottles or bags of contrast media. More often, a procedure will leave some portion of a bag or bottle remaining. In addition, contrast media may be left in the reservoir and tubing of a contrast media deliver system. Although the amount of contrast media which is wasted in a single procedure is relatively small, a medical facility which performs these procedures routinely will end up disposing a substantial amount of unused contrast media. Procedures and apparatus for minimizing the amount of contrast media which is wasted in a medical procedure are, therefore, highly desirable.
Methods for reducing the amount of contrast media wasted in a medical procedure would need to allow use of the remaining bottle or bag of contrast media on a subsequent patient and to eliminate contrast media remaining in the reservoir or tubing at the end of a procedure. The use of the contrast media remaining in the bag or bottle at the end of the procedure requires assurances that the contrast media has not been contaminated in some way by the original patient.
A number of systems for controlling contrast media to be delivered to a patient have been developed. These systems commonly will incorporate features designed to minimize the amount of contrast media which is wasted. A typical prior art system is shown in FIG. 1 of the appended drawings. FIG. 1 depicts a prior art contrast media control system, designated generally as 10, as it would be used in angiography and angiplasty procedures, hereinafter "angio procedures."
As depicted, such a system will typically include a contrast media source shown here as contrast media bag 12 but also available as a bottle (not shown). Contrast media bag 12 hangs on I.V. pole 14 and is contained integrally in cuff assembly 16 which acts as a pressurizer when hand pump 18 is used to inflate cuff 20. Pump valve 22 allows for inflation and deflation of cuff 20. When hand pump 18 is squeezed it acts to inflate cuff 20 and applies pressure to contrast media bag 12.
Contrast media bag 12 is accessed via bag connection assembly 24 to which inlet line 26 is connected. Two position inlet valve 28 is disposed in inlet line 26. Inlet valve 28 can be turned "on" by placing the fins of the valve in line with inlet line 26 as shown. In this position, fluid can flow from contrast media bag 12 through inlet line 26 to reservoir 30. Inlet valve 28 can, alternatively, be turned "off" by placing the fins of the valve perpendicular to inlet line 26 (not shown). In this position, inlet line 26 is closed and does not allow flow of contrast media from contrast media bag 12 through inlet line 26 into reservoir 30.
Upper one way valve 32 and lower one way valve 34 are also disposed in inlet line 26. These valves provide a redundant system for preventing contamination of the contrast media contained in contrast media bag 12 by preventing any fluid movement toward contrast media bag 12 from the point of the valve. Although a single one way valve would theoretically be sufficient, a dual one way valve system is used to ensure contamination is prevented. In this way, any contrast media remaining in contrast media bag 12 at the end of a procedure can be used for another procedure.
Reservoir 30 has a cap 36. Cap 36 has a inlet line connection 38 and a reservoir vent 40 disposed thereon. Contrast media flowing from contrast media bag 12 into reservoir 30 flows directly out of inlet line 26 and would, without intervention, fall to the bottom or fluid level of reservoir 30. The act of falling and splashing on the bottom of reservoir 30 or into the fluid in reservoir 30 can have the undesirable effect of causing micro bubbles in the contrast media. Micro bubbles injected into a patient can have serious side effects particularly in a system such as this where fluid may be fed directly into the heart. If a micro bubble were to lodge in the myocardia of the heart, it could stop the flow of blood and result in the death of that portion of the heart tissue. For such reasons, a deflector assembly (not shown) is typically employed to force fluid entering reservoir 30 to flow down the sides of reservoir 30.
Reservoir vent 40 allows contrast media to flow into reservoir 30 initially. Because the system is closed, even with inlet valve 28 in the "on" position, contrast media will not flow from contrast media bag 12 into reservoir 30. The system must be vented before the contrast media can flow to reservoir 30. This is accomplished by pushing on cap 42 which is disposed on reservoir vent 40. Cap 42 has a small slit cut therein which opens slightly when pressure is applied. When the desired level of fluid is reached in reservoir 30, the medical user releases cap 42 which allows the slit to close. With the cap back in place, contrast media will cease to flow to the reservoir and will only resume flowing if cap 42 is removed or some contrast media is removed from the reservoir.
Fluid flows out of reservoir 30 through outlet line 46. Ball valve 44 floats on any contrast media contained within reservoir 30. Ball valve 44 is designed to close off reservoir 30 when there is no contrast media remaining in reservoir 30. Unfortunately, these valves often leak to some degree often due to slight circumferential differences between ball valve 44 and outlet 48.
Contrast media flows through outlet line 46 to fluids administration system designated generally at 50. Fluids administration set 50 includes a syringe 52 which is connected to a catheter manifold 54 with a connection assembly 56. Syringe 52 includes a barrel 58 and a plunger 60.
Manifold fluid line 62 is defined by catheter manifold 54. Manifold fluid line 62 provides for movement of a variety of pressurized fluids through catheter manifold 54. Fluid flow is controlled by a number of manifold valves which are disposed in manifold fluid line 62. The flow of contrast media is controlled by contrast media manifold valve 64 which incorporates tab 66. Other typical manifold valves are represented by saline manifold valve 68 which incorporates tab 70 and pressure manifold valve 72 which incorporates tab 74. Each valve is associated with a fluid line. Contrast media manifold valve 64 is associated with outlet line 46. Saline manifold valve 68 is associated with saline line 76. Pressure manifold valve 72 is associated with pressure line 78.
Each fluid line is connected to catheter manifold 54. Outlet line 46 is connected via a contrast media connection assembly 80. Saline line is connected via a saline connection assembly 82. Pressure line 78 is connected via pressure connection assembly 84.
The operation of each manifold valve is identical. To stop a fluid from passing through the valve, the valve is turned so that the tab points toward the fluid line. In this position, the valve occludes the fluid line at which the tab is pointing. At the same time, the valve permits fluid to flow through the manifold fluid line 62. In FIG. 1, the tabs of all of the valves are pointing toward each respective line. This indicates that fluid is being allowed to pass through manifold fluid line 62. Concurrently, outlet line 46, saline line 76, and pressure line 78 are being occluded.
Opposite syringe 52 on catheter manifold 54 is a catheter connection assembly 86. A catheter (not shown) would be connected to catheter connection assembly 86 and would, thus, be connected to catheter manifold 54. During an angio procedure, various fluids would pass through catheter manifold 54 to a catheter (not shown) and then intracorporeally to a patient.
Focusing now on the administration of contrast media to a patient, the contrast media manifold valve 64 must be turned so that tab 66 is pointed toward syringe catheter connection assembly 86 in order for contrast media to be drawn into barrel 58 of syringe 52. When syringe 52 is filled to the desired level, the contrast media is then injected into the patient. The act of filling syringe 52 to the desired level and injecting the contrast media into the patient is commonly referred to as administering a bolus of contrast media.
As contrast media is drawn into syringe 52, reservoir 30 begins refilling to the level held prior to the drawing of contrast media into syringe. This occurs because the system is closed and the drawing of contrast media into syringe 52 creates a pressure differential which causes contrast media to flow into the reservoir. This pressure differential exist until reservoir 30 is refilled to its previous level.
As previously discussed, contrast media is expensive. When the medical professional is approaching completion of a procedure, therefore, he or she will turn off the supply of contrast media by placing inlet valve 28 in the "off" position. In this position, inlet valve 28 occludes inlet line 26 and prevents contrast media from flowing into reservoir 30. When this is done, the medical professional has effectively two boluses left. One bolus comes from the contrast media contained within the length of tubing comprising outlet line 46 and the second bolus from the contrast media contained within the reservoir.
When filling syringe 52 for these last two boluses the medical professional must work against the closed system. Filling syringe 52 for the second to last bolus results in substantially draining the reservoir into outlet line 46. This creates a vacuum effect in reservoir 30 which pulls against the action of syringe 52.
The vacuum effect is particularly strong when pulling the remaining fluid from outlet line 46 for the last bolus. The force is so strong in fact, that although plunger 60 of syringe 52 typically can be pulled back with sufficient force, nevertheless fluid does not flow into fill barrel 58 of syringe 52 for the last bolus. In order to overcome this vacuum effect, the medical professionally must overcome the seal of ball valve 44 and open vent 40 in reservoir 30, although it may be possible to dislodge ball valve 44 simply by flicking reservoir 30 with a finger.
More often ball valve 44 gets lodged and more elaborate steps must be taken. In order to dislodge ball valve 44, vigorous shaking or tapping of reservoir 30 may sometimes be required. Reservoir 30 may even need to be turned upside down to dislodge ball valve 44 As will be appreciated, this is less than desirable in the midst of a delicate medical procedure
Once ball valve 44 is dislodged the system can be vented to atmosphere by pushing on vent cap 42 to allow the system to vent through vent 40. Syringe 52 can then be filled with contrast media from outlet line 46 for administration of the last bolus.
A problem in the art of contrast media control systems is the creation of microbubbles from the contrast media falling into reservoir 30. Several additional problems are particularly apparent during the last two boluses of a procedure. Leaking around ball valve 44 is undesirable. The tendency for ball valve 44 to get lodged and require significant manipulation to dislodge is distracting at best. Applying pressure to vent cap 42 and dislodging of ball valve 44 in order to vent the system and to allow the last shots to flow easily from the reservoir and outlet line adds complexity to a procedure that is already delicate.